I had a similar issue (your symptoms were almost identical to mine) and it was the crank position sensor. I would come to a stop and it would idle way down and sometimes die. It was intermittent but enough of an issue to where it needed to be addressed. Luckily for me, the mechanic at the shop recognized the symptom and diagnosed it. They replaced it and 12000 miles later it has not occurred.

 

I'll do that once I'm convinced it's a thundermax issue. I am going to do the easy stuff first, you know, check for an intake leak, clean throttle body, and then I'll go from there.

That's the perfect way to describe the frequency of the problem. Is there a way to check the CPS? I'll have to take a look in the manual. Thanks.

 

I believe U codes have to be fixed first because they can cause rest of codes.

 

Your best bet would be to post a separate thread and ask that question. I believe that someone posted the procedure once before but without doing a bit of searching I am not sure where it is. However I do think it was in this section (Electrical/Ignition/Tuner/ECM/Fuel Injection)

 

So the problem persists despite my couple of attempts to remedy it. I cleaned out the throttle body, although it already looked pretty clean. I also tested for intake leaks and I have none. I also checked for loose connections but didn't see any. I think next I'm going to try putting back in the stock ECM. And yeah, as I was coming to work today, it tried to die on me a couple of times but I was able to keep it alive by laying on the throttle. Below I'm going to list all of the "symptoms" to give all you guys and possible clue.

Problems:
- Inconsistent idle. Every once in a while, the idle will stay at the regular rpm but it will surge on one of the cylinders. Has been going on for a while. Usually happens before slow idle.

- Can't Idle. Idle will start to slow way down until the bike dies. This has only recently started happening

- Both of these conditions don't necessarily happen only when the bike is stopped. It can happen while I'm coasting to a stop. As long as the throttle is at 0 TPS and the engine is at idle speed, it can happen. Otherwise the bike runs perfectly.

-Seems to happen at all temperatures, but I think it increases as it warms up.


That's all I can think of at the moment. Any ideas? Tomorrow I'm going to swap ECM's and see if that changes anything, that way I can narrow it down to the thundermax or something on the bike. Thanks.
-Theo

 

Theo,
Don't take me as being rude but I have question. Why did you switch ECM's to begin with? Both the Magnetti and Delfi ECM's are superb products. They can be programmed any way that you want.

I would really take a look at the timing on your engine. While idling (1000-1050 RPM) your engine will register 30 to 40 MAP (manifold Absolute Pressure) This is the area that you want to adjust your timing at. If you have a spark advance table in your T-Max software for the front and rear cylinder, adjust your timing down to 17.5 degrees before TDC for each cylinder for an RPM range of 750-1250 RPM's and in the 30-40% MAP load range. If this solves the problem and your exhaust doesn't smell like an old lawnmower, you should be good to go.
If not, drop it down to 16 degrees and smell the exhaust. Check the engine temperature and the idle. You want to be idling at at least 1000 RPM's to keep that oil running up to the top end. Your idle can be adjusted with the software too.

The other thing that you want to look at is the VE table or fuel table. The front cylinder should always have more fuel running into it than the rear cylinder while idling; but the rear should not be dramatically less. It should be about 3 to 5 milli-seconds of pulse width less than the front cylinder. If you increase the fuel at idle at 0% TPS, check to see if you are giving it too much fuel by smell and the color of your exhaust when you crack the throttle in you driveway. If you have an A/F ratio meter, this is the best and safest way to measure things.

Question; What kind of plugs are you running in your bike? When was the last time you looked at them?
Question; What does your exhaust look like when you crack the throttle?
Question; Is your battery holding a good charge?
Question; was this big bore and cams put in by you or someone else?

 

Ok I have an update. I really hope I'm not jumping the gun but I think I fixed the problem. I swapped the thundermax ecm for the stock one and rode to work without any problem. But I'm going to keep riding with the stock ECM for a week to be totally convinced. I want to thank all of you, especially you producer for taking the time to help me with my problem. Hopefully I won't need anymore. If this truly is a thundermax problem, I'll get in touch with Zippers and I'll update this thread with what they say. Thanks.
-Theo

 

Theo,
You are very welcome. Keep up the good fight! see you soon!

 

Alright well I have an update finally. So it turns out I was half right, sort of, about it being the IAC. The map I was using was made with a larger aftermarket throttle body in mind, so it was closing up the IAC too much for my stock throttle body. Zippers gave me a revised map and the bike has been performing flawlessly since. Well that's my update. And if you don't hear from me again, consider the problem resolved. Once again, thanks to all that responded and helped.
-Theo